The proposed conference on Contractile Proteins will be the 19th in a series of Gordon Research Conferences that originated with a conference on cardiac muscle in 1966. The major focus of this conference will be the molecular basis for muscle contraction. This knowledge impacts on other fields such as cell motility and microvillar function where actin and myosin play important dynamic and structural roles. Recently, hypertrophic cardiomyopathy was shown to be linked to mutations in the cardiac myosin heavy chain gene and so understanding of the function of myosin may lead to insight into the pathological condition. The conference will consist of approximately 25 formal presentations by invited speakers. In each of the eight sessions, two to three people will be asked to give short presentations based on information contained in their posters. This format will leave ample time for in depth discussion of the results. The session chairperson will try to integrate the discussion and the short presentations to integrate with the data presented in other sessions so that a better understandings of the problems are reached. The meeting will include a Sunday evening lecture on some aspect of cell motility that will demonstrate the function of actin or myosin in a nonmuscle cell or acquaint the participants with some other force generating system such as kinesin. The high resolution crystal structure of myosin subfragment-one (session 1) will be a highlight of the meeting and should provide a basis for interpreting data presented in sessions 2 and 4 where the function of mutated conventional myosin or the characterization of novel forms of myosin will be presented. Session 3 will rely heavily on the crystal structure of actin that was presented in the last Gordon Conference on Contractile Proteins and on the structure of troponin C. The mechanics of muscle fibers (session 7) and the dynamics of crossbridges during contraction (session 5) will be compared directly to the mechanics of the interaction of single actin filaments with small numbers of myosin molecules in vitro in session 6. Finally, the role played by titin, nebulin and twitchin will be examined in session 8. The ongoing work in cloning and sequencing these proteins are greatly aiding this pursuit by allowing for the production of site-directed antibodies and of expressed recombinant fragments of the various proteins which can be tested in in vitro actin and myosin binding experiments. The final session will be a moderated discussion in which leaders will address the unanswered questions and the points of controversy as well as summarize novel data that impacts on our understanding of muscle. The integrated approach to the study of muscle function proposed in this conference should yield a better understanding of the molecular mechanisms inherent to muscle contraction.